Fertilization of Sphagnum bogs, on the basis of certain field experiments at Leteensuo

The present investigation is an account of the results from two fertilizing experiments established on Sphagnum bog at the Experimental Station of Leteensuo. The experiments were carried out in 1923 and 1934. The following conclusions can be drawn from the results. Most important in significance among the different nutrients is nitrogen, phosphorus ranging next, and potassium last. Potassium could even cause a reduction in the crop yields. The effect of liming was evident in the form of increased hay crops, whereas the grain yields of oats were reduced by it. Liming has improved the effect of phosphorus particularly in the case of hay. The results also seem to indicate that the relation between potassium and calcium has significance in regard to the reduction of crop yield caused by potassium. Remarkable crop yield increases were obtained by nitrogen fertilizing. The hay crops and the grain and straw crops of oats increased almost linearly with the addition of nitrogen, in the form of calcium nitrate, in quantities up to 90 kg N per hectare. Quantities in excess of this caused hardly any further increase in the crops. The said quantity is suitable for cover manuring of hay meadows, but the most advisable quantity for cereals is thought to be 45—60 kg N per hectare, so that lodging of the crops might be avoided. Nitrogen fertilization does not essentially affect the quality of the grain crops of cereals; on the other hand nitrogen promoted the retention of timothy in the meadow when nitrogen was used in quantities up to 90 kg per hectare. Stable manure increased the crops. This effect was most distinctly evident in the grain and straw crops of oats. The effect of stable manure was still present 15 years after the most recent addition of stable manure.